Ferroelectric properties of BiFeO3 nanodots shattered by atomic force microscope

A BiFeO3 (BFO) nanodot was deposited on a Nb-doped SrTiO3 substrate by dip-pen nanolithography. The BFO nanodot had a diameter of about 50 nm after drying and annealing to remove the solvent contained in the nanodot. To make nanoparticles smaller than a few tens of nanometers, the BFO nanodot was then shattered using an atomic force microscope. Ferroelectric BFO nanodots smaller than 20 nm in diameter were successfully fabricated after the annealing process. A ferroelectric BFO nanodot smaller than 15 nm exhibited good ferroelectric properties with a canonical piezoelectric hysteresis loop and tunneling currents depending on ferroelectric polarizations.